Retaining device



NOV# 8 1949 c. M. cARlNGToN ErL 2487098 RETAINING DEVICE 2 Sheets-Sheet 2 Filed Feb. 20, 1946 1 n v u r rw www .wcm mimi NM QM Ton X mi We WMA Patented Nov. 8, 1949 RETAINING DEVICE Charles Molyneux Carington and Walter Jonathan Pickett, assignors to K. L. G. Sparking Plugs Limited, London, England, a British company Application February 20, 1946, Serial No. 648,987 In Great Britain December 22, 1944 Section 1, Public Ilaw 590, August 8, 1946 Patent expires December 22, 1964 8 Claims. l

This invention relates to retaining devices and has for its object to provide means for retaining one end of a rod-like part in a socket against Withdrawal therefrom. 1t may be used in various circumstances and one example, which will be described later, is the retaining of the end of an ignition cable in an insulating sleeve for use in the ignition system of an internal-combustion engine.

According to the present invention there is provided the combination with a rod-like part and a socket to receive one end of said part, of means for retaining the said end of the part in the bore of the socket, comprising cci-operating shoulders provided respectively on the said end of the part and in the bore of the socket so that they can be engaged with, or disengaged from, one another by a lateral movement of the said end of the part in the bore of the socket, and means for holding the said end against lateral displacement from the position in which the shoulders are engaged.

According to a feature of the invention, one shoulder has a circumferential extent of 360 whereby it can be engaged by the other shoulder in any angular position of the part in the socket.

Preferably the shoulders are engaged when the part is situated centrally in the bore of the socket and disengaged by movement of the part laterally from the axis of the bore and the holding means is arranged to centralise the part in the bore. Conveniently the shoulders are each constituted by the front face of a flange and the back face ci one or each nange is tapered so that the inner end of the part is displaced laterally, when it is pushed into the bore, by the engagement of the back faces of the flanges. The holding means may comprise a part slidable in the bore and spring-loaded to engage the inner end of the part and centralise it and also to press the shoulders axially into engagement.

The application of the invention to retaining one end of a high-tension ignition cable in the terminal will now be described, by way of example only, with reference to the accompanying drawings in Which- Figure l iS an axial section through the terminal with the end of the cable incompletely inserted;

Figure 2 is a similar section through the terminal and cable with the end of the cable comn pletely inserted;

Figure 3 s a section on the line 3-3 of Fig ure 1;

Figure 4 is an axial section through a portion of a modified construction, and f Figure 5 is a section through a portion ci another lnodied construction.

The terminal comprises an insulating sleeve I8 which has two coaxial cylindrical bores H and i2 extending one from each end and terminating just short of one another. The end i3 of the bore H, the receiving bore, is conical While the end i4 of the bore l2, the contact bore, is fiat. The bores communicate by a third cylindrical bore l5 that is eccentric to the bores H and i2 as shown in Figure 3 and its radius is less than that oi' the receiving bore Il by the amount or the eccentricity so as to form a crescent-shaped flange it between the bores ll and i2. As shown, the diameter of contact bore l2 is less than that of the receiving bore il and the diameter of the communicating bore l5 must be less than that of the bore l2 and extends a short distance beyond the hat end I4 of the bore l2 so that the bores l2 and l5 overlap. It will be noted that these bores can be formed quite easily by drilling or moulding and the bore l2 can be the same diameter as the bore H or of larger diameter if this is found desirable.

It will be noted that the flange i6 has a crescent-shaped conical face i3 on one side and a crescent-shaped flat face i4 on the other side.

The contact bore contains a cylindrical resistance unit l1 Which has a metal cup i3 on its inner end. A conventional Contact is mounted in the mouth of the contact borel i2 and comprises a split sleeve i9 which is rather larger than the bore so that it is compressed radially and retained in the bore by friction. Two metal thimbles 20 and 2l project from the ends of the sleeve i9 and are separated by a spring 22 in compression between them. The thimble 2! projects from the insulating sleeve it, while the thimble 2i] engages the resistance unit Il' and holds the cup E3 against the liange i6. f

The cable comprises a stranded wire 23 (Figure 2) in a flexible insulating sleeve 24. A errule 25 is secured on the end of the cable by inserting the bared end of the wire 23 through a tapered bore 26 in the ferrule and then inserting a needle point 2'! to spread the wires in the bore. The ferrule is provided with a radial flange 28 of which the face 29 constitutes a flat annular shoulder. The peripheral portion 30 Oi the other face of the flange 2t is flat and surrounds a conical portion 3 l When the end of the cable is pushed into the receiving bore Il, the ferrule 26 is centralised with the bore Il, shown in Figure l, until it engages the crescent-shaped conical face I3 which deects the ferrule laterally towards the communicating bore of the sleeve. The diameter of the iiange 23 is less than that of the bore I5 so that the ferrule can pass through it, the resiliency of the sleeve 24 permitting the necessary deection of the ferrule. In practice, the end of the cable will usually be inserted before the contact and the resistance unit are inserted. As soon as the shoulder 29 on the ferrule has passed the crescent-shaped flat shoulder I4 on the insulating sleeve, the ferrule can again centralise itself owing to the resilience ci the cable. The ferrule will then be in the position shown in Figure 2 in which the shoulders 29 and I0. are engaged with one another. The resistance unit and the contact are then inserted and the spring 22 is compressed as shown in Figure 2 and presses the cup I8 against the annular face 3B of the ferrule. The conical portion 3l of the ferrule lies within the cup I8 and this holds the ferrule in a central position since it must move the cup axially against the bias of the spring 22 if it is to move laterally from its central position. It is impossible to apply suiilcient lateral force to the ferrule by manipulating the cable to overcome the bias of the contact spring 22 so that the cable cannot become disengaged. It is also possible to insert the end of the cable while the resistance unit and contact are in the sleeve I i3.

To withdraw the cable from the insulating sleeve I0, the contact unit lli- 22 is removed together with the resistance unit Il. The cable is then pulled and turned simultaneously and the ange 28 on the ferrule will then, usually, iind its Way out through the bore I5. If it does not do so, the ferrule can be displaced laterally by a pointed instrument inserted through the contact bore I2 and the cable pulled out. If desired, a hole 32 may be provided in the sleeve in front of the shoulder I4 so that the ferrule can be moved laterally by inserting a pin through this hole. The contact unit I922 need not, then, be removed when the cable is withdrawn. This hole will, however, reduce the length of the flashover path and should not be provided if the voltage is so high that the full length of the sleeve I is necessary to prevent iiash-over.

In the modication shown in Figure 4, the communicating bore I3 is concentric with the bores II and I2 so that the shoulder Iii is annular instead of being crescent-shaped. The flange 2B on the ferrule is eccentric so that the shoulder 29 on it is crescent-shaped. The end 3l of the ferrule is cylindrical and the cup I8 is made conical internally so that it will act to centralise the ferrule. The operation of inserting and removing the cable is as previously described. The construction shown in ,Figures 1 to 3 is preferable.

In each of the arrangements described one of the shoulders I 4 and 29 is a complete annulus and this permits of the cable being turned in the sleeve. This feature is desirable but is not necessary if the cable and sleeve are so shaped that they cannot turn relatively to one another. By arranging that the ferrule 25 is alined with the part I'I when it is fully engaged in the sleeve, the natural resiliency of the cable is used for holding the ferrule.

The device may be modified, however, so that the ferrule is moved laterally of the axis oi the receiving bore I2 and is itself fully engaged. This modication is shown in Figure in which the receiving bore II and terminal bore I2 are not coaxial and overlap so that a crescent-shaped shoulder I4 is formed on which the ferrule will be engaged by a lateral movement produced by the pressure of the cup I8 on the conical portion 3| of the ferrule. This arrangement will not, however, retain the cable in the sleeve I as securely as the arrangements rst described.

The arrangements described above may be employed with suitable modifications for securing the end of a cable in any form of socket and for securing any other rod-like part in a socket. When the rod-like part is rigid it should be arranged to have lateral movement in the receiving bore of the socket or, preferably, to have the ferrule mounted resiliently on its end.

We claim:

1. The combination with a unitary rod-like part and a socket to receive one end of said part, of means for retaining the said end of the part in the bore of the socket, comprising co-operating shoulders provided respectively on the said end of the part and in the bore of the socket so that they can be engaged with, or disengaged from, one another by a bodily lateral movement of the said end of the part in the bore of the socket, and means for holding the said end against lateral isplacement from the position in which the shoulders are engaged.

2. The combination according to claim 1, wherein one shoulder has =a ycircumferential extent of 360,1and the other shoulder has a circumferential extent of less than 360 whereby the first shoulder can be engaged by the second shoulder in any angular position of the part in the socket.

3. The combination according to claim 1, wherein the shoulder in the bore is crescentshaped and extends only partly therearound and the shoulder on the rod-like part is circular and coaxial therewith so as to engage the shoulder in the bore when the rod-like part is centralized therein and wherein the holding means comprises a part spring-loaded to engage the rod-like part and centralise it.

4. The combination according to claim 1, wherein the shoulder in the bore is annular and co-axial therewith and the shoulder on the rodlike part is crescent-shaped and eccentric to the axis of the rod-like part so as to engage the shoulder in the bore when the rod-like part is centralized therein and wherein the holding means comprises a part spring-loaded to engage the rod-like part and centralize it.

5. The combination according to claim 1, wherein the bore in the socket is formed as two coeaxial portions of circular section communicating with one another by a third portion which is circular in section and of smaller diameter than either of the first two portions and has its axis parallel and spaced from the common axis of the first two portions to provide the shoulder of crescent shape in the bore, and wherein the shoulder on the rod-like part is annular, co-axial therewith and of external diameter slightly smaller than the third portion of the bore and the holding means comprises a part spring loaded to engage the rod-like part and hold it co-axial with the iirst two parts of the bore.

6. The combination according to yclaim 1, wherein the shoulders are formed by one face of an internal flange in the bore of the socket and one face of an external flange in the rod-like part respectively and the other face of said internal flange is tapered to form -a camming surface which deflects the rod-like part laterally in the bore when said part s moved axially into the bore.

7. The combination according to claim 1, wherein the holding means comprises a holding part slidable axially in the bore and a spring loading it to move it towards the shoulder in the bore and wherein the said holding part and the rod-like part are formed with co-operating cam surfaces by which lateral movement of the rodlike part in the bore from the position in which the shoulders are engaged moves the holding part axially against the load of the spring.

8. The combination with an insulating sleeve which has a cylindrical bore open through one end of the sleeve and terminating in a conoidal surface at its inner end, has a second co-aXi-al cylindrical bore open through the other end of the sleeve and terminating at its inner end in a surface normal to its axis, and has a third cylindrical bore of smaller diameter than the other bore opening into the inner ends of the other bores and having its axis parallel to that of the other bores and spaced therefrom by `a distance substantially equal to half the difference between its diameter and that of the rst bore, of a part lling and slidable in the second bore and having its inner end cup-shaped, a spring contact secured in the second bore to engage the part and resiliently bias it to move to the inner end of said bore, a cable having a flexible insulating sheath and a conducting core, and a ferrule secured on the end of the core and formed with an annular co-axial flange of slightly smaller external diameter than the third bore of the sleeve and with a co-axial conical portion on the side of the ange remote from the cable.

CHARLES MOLYNEUX CARINGTON. WALTER JONATHAN PICKETT.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS 

